94 175 Ocean Runner Flat Spot?

[CatTwentyTwo]

I normally run my engine at 3500 to 4000 RPM and it runs great, but with all the talk recently about what WOT RPM should be, I wanted to see what mine was. From 3500 RPM I went to full throttle and the engine pulled strong up to 4900 and then it stumbled and actually dropped a 100 RPM for a second or two and then it recovered and pulled strong to 5400 RPM. I repeated this three times with the same results. Is there some things I can check, or should I just not worry about it as I don't run in that range anyway?

 

[Dhadley]

Re: 94 175 Ocean Runner Flat Spot?

We need a bit more info to get a better idea of what we're looking at. What spark plugs are you using (please dont say "the right ones" -- exactly which ones?)? What grade fuel and is it fresh (how old)? Premix the oil or injected? What brand & type oil?

 

[CatTwentyTwo]

Re: 94 175 Ocean Runner Flat Spot?

The plugs are brand new QL77JC4's, the gas is Chevron regular grade treated with 2+4 at the storage cocentration and is 2 months old. I use the standard Evinrude 2 stroke oil along with the original VRO system. <br />I should add that I don't use the boat as much as I should, so it sits for extended periods, but I always use 2+4 and after 6 to 8 months I drain out whats left and add fresh gas.

 

[Dhadley]

Re: 94 175 Ocean Runner Flat Spot?

OK, good choice on plugs, fuel and oil. Just as an FYI -- you don't have a VRO pump. Its a straight ratio fuel/oil pump. Not an issue until you work on it and look for VRO parts. Thats when it can get confusing.<br /><br />Anyway I'd start with a good cleaning of the carbs and OE kits. We need to get the r's up a bit so its easier on the motor throughout the entire range. And so the motor will live longer. <br /><br />Take a close look at #1 plug and make darn sure that plug looks exactly like the rest after you run a while.

 

[CatTwentyTwo]

Re: 94 175 Ocean Runner Flat Spot?

Thanks Dhadley, I will make the carb cleaning my winter project. Can I just remove the carburetor bodies or should I remove the whole throttle body assemblies? Is there any need to look at the vapor separater at the same time? I assume I will need to have a dealer do a link and sinc afterwards.<br />I must say I am totally confused about the oil pump. My OMC service manual refers to it as a VRO2 pump. <br />Thanks again, I have learned so much from your posts.

 

[CatTwentyTwo]

Re: 94 175 Ocean Runner Flat Spot?

Can any one help me with my last couple of questions from above?